Signaling system



Aug. 7,, 1923; 1,,464D9U I J. c. FIELD ET AL S IGNALING SYSTEM Filed July 14 1919 Patented Aug. 7, i923.

UNITE STATES P T 3F i i 6E a JOSEPH C. FIELD, OF EAST ORANGE, NEW JEItSEY, AND CHARLES J. IVIGCABTHY, 0F

ELMHURST, NEW YORK, ASSIGNOBS TO WESTERN ELECTRIC COMPANY, INCORPO- RATED, OF NEW YORK, N. '55., A CORPORATION OF NEW YORK.

SIGNALING SYSTEM.

Application filed July 14, 1919. Serial No. 310,815

To all whom it may concern:

Be it known that we, Josnrrr C. FIELD and CHARLES J. MCCARTHY, citizens of the United States, residing at East Orange, in the county of Essex and State of New Jersey, and at Elmhurst, in the county of Queens and State of New York, respectively, have invented certain new and useful Improvements in Signaling Systems, of which thefollowing is a full, clear, concise, and exact description.

This invention relates to signaling sys tems and more particularly to selectively operated signaling systems in which a plurality of waystations connected with a singleline circuit are each provided with a selectively operated signal controlling device. i

The object of this invention in general is to provide an improved organization of apparatus andcircuits whereby any party on a circuit may without assistance call any other party on the same circuit without op erating the signals at any of the other stations, and may receive an indication that the signal at the called station has operated.

In accordance with the general features of this invention the selectively operated devices are each simplexed to ground from the mid-point of an inductive bridge comprising condensers and impedance coils; a key is provided at each waystation for charging and discharging the inductive devices of each bridge through the selectively operated device associated therewith and from a common source of energy which is connected in simplex of the line through a high impedance retardation coil; and a signaling device provided at each station and controlled by the selectively operated device thereat when operating intermittently completes a local circuit inductively coupled with the line through the coils of the associated transformer, whereby an indication that the Sign nal at the called station is operating is trans mitted to the calling station.

The drawing is a. diagram of the circuits and apparatus illustrating this invention.

In the drawing 5 and 6 designate a pair of line wires with which are associated a plurality of waystations of which only A and B are shown. At ea h of the waystations there is a selectively operated signal controlling device comprising in general a polarized operating magnet 7 and stepping means controlled thereby for advancing step-by-step into contact-engaging position a step-by-step contact carrying element 8. The contact carrying element 8 which is mounted upon a shaft 10 is provided with a movable contact 9. A ratchet wheel llis also mounted upon the shaft 10, and both the contact carrying element 8 and the ratchet wheel 11 are held inthe position shown by means of a coiled spring 12, one end of which is fixed and the other end secured to the shaft 10. This contact carrying element 8 is adapted to be advanced stepby-step into position. for causing the movable contact 9 to engage the stationary contact 13. The operating magnet 7 is pro vided with a centrally pivoted armature 20 which carries an S-shaped arm 21. This S-shaped arm 21 is provided with two pins 22 and 23 so positioned that they impinge upon opposite faces of a pivoted rocker arm 24. This rocker arm 24 carries at its outer end a stepping pawl 25 and. at its inner end a pin 26 which impinges upon the tail piece of the pivoted holding pawl 27. The coiled spring 28, one end of which is fixed and the other end attachedto the tail-piece of the holding pawl 27, tends to move the holding pawl into engagement with the ratchet wheel 11, but normally this is prevented by the action of the pin 26. 3A coiled spring 29, fixed at one end and at its other end secured to the rocker arm. 24., serves normally to maintain the rocker arm 24, the S-shaped arm 21, and the centrally pivoted armature 20 in the position shown. The pin 26 also impinges upon a spoonended holding spring 30 so that upon each energization of the operating magnet the pin 26 causes the spoon-shaped end of the holding spring 30 to be moved outside of the path of holding pins 31, 32 and 33 provided in the contact carrying element 8. Upon each energization of the operating magnet 7, the stepping and holding pawls through the action of the S-shaped arm 21 and. the rocker arm 24: are caused to engage the ratchet wheel 11 to advance this ratchet wheel and the contact carrying element .8

one step against the action of the coiled spring 12. The holding pawl 27 serves to maintain the ratchet wheel and contact'carrying element in advance position during a reversal of current through the windings of the operating magnet 7. During each reversal of current through the windings of the operating magnet 7 the S-shaped arm. 21 and the rocker arm 24 return to normal position so that the spoon-shaped end of the against the action of the coiled spring 12 until further impulses are transmitted thropgh the windings of the operating ma; net

The selectively operated signal controlling devices illustrated. in the drawing are of the type disclosed in PatentNo. 1,343,256 June 15, 1920, and are each adapted to respond to a definite code of impulses. The selective devices at the Various stations are moved into contact-engaging position in response to the same number of impulses but these impulses are divided into groups, the number in each group varying for the different stations. The position of the intermediate holding pins 31 and 32 determine the station at which the contact carrying element 8 will be moved into contact-engaging position. It will be understood that in transmitting the impulses, those of the first group will be followed by a pause to permit the return to normal position of the contact carrying elements at all stations where the first intermediate holding pin 31 is not positioned so that it is engaged. by the spoon-shaped end of the holding spring 30 upon the eessation of the last stepping impulse of the group. In a similar manner the contact carrying elements at all other stations ex cept the desired station will be eliminated by the second group of impulses, the third group of impulses advancing the contact carrying element of the desired station into contact engaging position. It will be seen therefore that in response to a predetermined combination or code of transmitted impulses, the contact carrying element at but one of the stations will be moved into contact engaging position. After contact carrying element 8 has been moved into contact engaging position and held there by the spoon-shaped end of the holding spring 30 with the holding pin 33, the element may be returned to normal position by advancing bell is a contact 56.

it one or more steps so that upon the cessation of the advancing or stepping impulses, the spoon-shaped end of the holding spring 30 will in moving to normal position not engage the holding pin The coiled spring 12 thereupon returns the element to normal position.

Connected to the line wires 5 and 6 at each of the way stations is an inductive bridge comprising impedance coils 41, 42, 43 and 44, all of which are mounted upon the same core, and two condensers 45 and 46. As will more fully hereinafter appear, these coils serve as an auto-transformer to inductively couple a local answer back circuit with the line circuit. The coils and the condensers of each bridge are included in serial relation with respect to each other. One side of each of the operating magnets 7 is connected with ground, the other being connected with the inductive bridge at a point betweenthe condensers 45 and 46. A battery 47 located at one end of the line wires 5 and 6 is connected in simplex of the line wires through a high impedance, low

resistance retardation coil 48 and the windings 49 of a simplex coil.

Located at each of the waystati-ons is a key lever 50 connected between the condenser 45 and the line wire 5 and cooperating with contact springs 51 and 52. Contact spring 52 is connected with ground and is adapted to be engaged intermittently by the lever 50 during the operation of the key in calling while contact spring 51 is connected between condenser 46 and the line wire 6, and is adapted to be engaged continuously by the key lever 50 during the operation thereof.

At each waystation there is provided a call bell 55 connected in a normally open local circuit which is closed by the engagement of the movable contact 9 with the sta tionary contact 13. Provided on the call This contact 56 is normally open for the purpose of discon necting a source of battery 60 from the line conductors during the period the selector equipment at the way station 18 inoperative.

By having-the contact 56 normally open, a single source of battery may be utilized for providing operating currents for a plurality of selectors located at one way station. During the operation of the call bell 55- upon such a closure of its local circuit, con tact 56 is intermittently closed thereby intermittently establishing a local circuit .which may be traced from contact 56,

through condenser 57 coil 42, condenser 45, holding spring 30, holding pin 33, contact carrying element 8, movable contact 9, stationary contact 13, and left-hand winding of the call bell 55 to the contact 56. After the closure of contact 56 and prior to the opening of contact 58 of the call bell 55, the local battery 60 is in parallel with the lefthand winding of the call bell 55, but this is removed from the circuit immediately upon the opening of contact 58. This local circuit which has been traced is inductively coupled with the line wires 5 and 6 through the coils 41 to 14: inclusive whereby there is transmitted to the line an answer-back signal which may be heard in the receiver bridged across the line Wires at the calling station. A telephone set comprising a transmitter 61, a receiver 62, the usual inductance coil 63, and switching devices is provided at each waystation.

The operation of the system is as follows: Normally the condensers 45 and 46 are charged to the potential of the battery 47. lVhen the calling key at any station is operated, the key lever 50 engages the contact spring 51 and remains in engagement therewith during the complete operation of the key. The key lever 50 is caused to intermittently engage the contact spring 52 to give the correct combination of impulses to operate the selector at the station called. Each time that the lever 50 engages the contact spring 52 the condensers 45 and 46 at each of the waystations are discharged through their associated selector windings, and when the key lever 50 disengages the contact spring 52, the condensers 45 and 46 charge through the windings their-associated selectors, thus causing the flow of current im pulses through the winding of the operating magnets 7 alternating in opposite directions to advance the step-by-step carrying elements 8 until the station contacts of the desired station are closed. Upon the cessation of the last stepping impulse the spools shaped end of the holding spring 30 at the called station engages the holding pin 33 to maintain the element 8 in contact engaging position. The local circuit including the operating windings of the bell 55 at the calledstation is thereby closed causing the operation of the bell. During the operation of the call bell 55 the source of battery 60 will be inductively connected across the line through the medium of the auto-transformer. Upon each energization of the left hand winding of call bell 55, its armature will so move as first to close contact 56 and then to open contact 58. The closing of contact 56 connects the battery 60 in series with the condenser 57 which is thereupon charged in accordance with the potential of the battery 60. Consequently, upon the opening of the contact 58, a circuit is established from the condenser 57 through winding 42, condenser 45, holding spring 30, contact carrying element 8, movable con tact 9, stationary contact 13, left hand winding of hell 55, contact 56 to condenser 57, through which circuit condenser 57 is discharged so as to energize winding 4-2. The energization of thiswinding causes current to be generated in the other windings of the auto-transforn1er bridging the lmeconduo tors 5 and 6, and operates to give an answerback signal in the receiver 62 at the calling 1. In a signaling system. a metallic line circuit, a plurality of stations associated therewith, an inductive device comprising a plurality of windings at each station connected in bridge of the line circuit, a selector at each station connected between the midpoint of the inductive bridge and ground, a source of current, means for operating all of the selectors from said source, a signaling device controlled by each selector, and a local circuit controlled by each signaling device and inductively coupled with the line circuit through the windings or" the inductive device.

2. In a signaling system, a metallic line circuit, a plurality of stations associated therewith, an inductive device comprising a plurality of windings at each station connected in bridge of the line circuit, a selector at each station connected between the mid-point of the inductive bridge and ground, a source of current, means at each station for operating all of the selectors from said source, a signal device controlled by each selector, and a local circuit controlled by each signaling device and including a winding of the associated inductive device.

3. In a signaling system, a line circuit, an inductive bridge across said line circuit, an electromagnetic device connected with said inductive bridge, a source of current, means including said line circuit and the inductive body for selectively operating said electromagnetic device from said source of current, a signaling device controlled by said electromagnetic device, a local source of current to operate the signaling device, and a normally open local circuit connected to said inductive bridge completed upon the operation of the signaling device for connecting a portion of said inductive bridge with said local source of current.

4:. In a signaling system, a line circuit, an inductive bridge across said line circuit, an electromagnetic device connected with said inductive bridge, a source of current, means including said line circuit and the inductive body for selectively operating said electromagnetic device from said source of current,

a' signaling device controlled by said electhe line circuit through a portion of said intromagnetic device, a local source of current ductive bridge. to operate the signaling device and a nor- I In witness whereof, We hereunto subscribe mal'ly open local circuit connected to said our names this 8th day of July A. D., 1919.

5 inductive bridge completed upon the operation of the signaling device for inductively JOSEPH C. FIELD. connecting said local source of current with CHARLES J. MCCARTHY. 

